Former exec at real estate syndicate Property Research started storage business 1972 after stopping at warehouse on road trip and learning it was full. Lost potential customers with confusing signs: people thought "Private Storage" meant closed to general public. New name brought them in droves. Today Public Storage nation's largest self-storage company. Bought rival Shurgard for $5.5 billion in 2005. Staunch Republican gave $1 million to Schwarzenegger in 2005, $500,000 to ultraright Progress for America in 2006. Horse racer seeking first Kentucky Derby win.